1. Field of the Invention
The present invention relates to the field of communication systems. More specifically, the present invention relates to equipment for home audio/video electronics.
2. Related Art
A typical home audiovisual equipment complement includes a number of components, e.g., a radio receiver, a CD player, a pair of speakers, a television, a VCR, a tape deck, etc. Components are connected to each other via sets of wires. One component is usually the central component of the home audiovisual system. This is usually the radio receiver, or the tuner/decoder. The control buttons and control switches are usually located on the front of the tuner and in many cases, some or all of these buttons and switches are duplicated on a hand held remote control unit. A user controls the home equipment by manipulating the buttons and switches on the front of the tuner, or alternatively, manipulating buttons on the hand held remote control unit.
As consumer electronic devices have become more capable and more complex, demand for the latest and most capable devices has increased. As new devices emerge and become popular, new devices are purchased by consumers and "plugged" into their home audiovisual systems. The new device is simply plugged into the system alongside the pre-existing, older devices (e.g., cassette tape deck, CD player, and the like). The new device is plugged into an open input on the back of the tuner, or some other device coupled to the tuner. The consumer (e.g., the user) controls the new device via control switches on the new device itself, or via a separate remote control unit for the new device.
As the number of new consumer electronics devices for the home audiovisual system has grown and as the sophistication and capabilities of these devices have increased, a number of problems with the conventional paradigm emerge. One such problem is incompatibility between devices in the home audiovisual system. In addition, where one device is much newer than another device additional incompatibilities may exist For example, a new device might incorporate hardware (e.g., specific inputs and outputs) which enables more sophisticated remote control functions. This hardware may be unusable with older devices within the system. Another problem is the lack of functional support for differing devices within an audiovisual system. For example, even though a television may support advanced sound formats (e.g., surround sound, stereo, etc.), if an older less capable tuner does not support such functionality, the benefits of the advanced sound formats car be lost. Another problem is the proliferation of controls for the new and differing devices within the home audiovisual system. Each new device coupled to the audiovisual system often leads to another dedicated remote control unit for the user to keep track of and learn to operate.
In view of the above, it is desired to provide a communication architecture in which consumer electronics devices can be integrated. In so doing, the consumer electronics devices can offer and be expanded to include advanced communications and control functionality between themselves not heretofore offered. Within such communication architecture integrating consumer electronic devices ("a consumers electronics network"), devices can communicate with each other and control one another. Within a communications network where devices can communicate and control other devices, it is important that devices and associated software objects be aware of the current status of devices in the network to provide effective communication, control and reporting functions. Therefore, what is desired is a system that can efficiently report device status information to other devices and software objects within the communication network while requiring a minimum of high level application effort.
The IEEE 1394 serial communication bus, according to the IEEE 1394 standard, assigns a 6-bit physical identifier value (phy.sub.-- id) to each device connected to the bus. The IEEE 1394 serial communication bus uses this physical identifier to communicate with a device coupled thereto. Whenever a new device is inserted onto the bus (or powered on), or an existing device is removed from the bus (or powered down), or both, a bus reset is caused. The bus reset initiates certain well known bus recovery communications and functions in accordance with the IEEE 1394 standard.
The above described bus reset initiates certain well known bus recovery communications and functions in accordance with the IEEE 1394 standard, including the possible renumbering of the physical identifiers of the devices remaining on the IEEE 1394 bus after the bus reset. That is to say, the physical identifiers assigned to devices on the IEEE 1394 bus are not always preserved (e.g., not persistent) following a bus reset.
However, it is also desired within the consumer electronics network that high level applications adopt abstract and persistent identifiers for devices within the network. Since many data structures (e.g., speed map and topology map) and communication channels are maintained and implemented within the IEEE 1394 standard using physical identifiers, a problem exists for high level applications that use a persistent identifier for each device but also need to communicate with the devices of the network and/or need access to speed map and topology data. What is desired is a mechanism and method operable within a consumer electronic network that provides an IEEE 1394 communication framework, but also efficiently provides high level applications with a persistent identifier for devices coupled to the network.